Think 3D Free for iOS

Think 3D Free lets you create projects using a variety of 3D shapes that you can add to, rotate and manipulate in space, and save images of. Choose from 11 different types of projects, and build structures with vibrant colors that are fun to experiment with and observe.

This app opens with two sample projects already created for you to play with and add to if you choose. Tap a project to get started, or choose to create your own new one by tapping the "+" icon in the upper left-hand corner of the interface. This will bring up a list of the different types of shapes you can use for your project, including different kinds of regular polyhedra, uniform polyhedra, irregular tetrahedra, and combinations. When you've chosen your building blocks, you can move on to the creation screen. Here you'll see one of the shapes you've chosen displayed, and you can add to it by tapping the "+" icon on the bottom toolbar and then tapping on the screen in the spot you want to add another block. Continue to add and subtract using these tools, and rotate the image at any time by dragging your finger in the direction you want it to turn. You can also change the colors of the blocks by tapping the color tool and selecting from the pop-up window.

Pinching causes you to zoom in and out, and you can save any image by tapping the Export icon and selecting a destination. To start a new project, go back to the main project menu and begin again. All of your projects are saved here in a scrollable list with thumbnail images so you can go back to them at any time. The app is free, has a highly intuitive interface, and it runs well, making it a fun choice for all ages.